1. Field of the Invention
The present invention relates to a spindle motor for rotating a disk about a central axis and a disk drive apparatus provided with the spindle motor.
2. Description of the Related Art
A hard disk drive or an optical disk drive is equipped with a spindle motor for rotating a disk about a central axis. The spindle motor includes a housing, a stator unit fixed to the housing and a rotor unit arranged to hold a disk and rotate together with the disk.
There is conventionally known a spindle motor of the type including a magnetic attraction plate attached to the upper surface of a stator unit. The magnetic attraction plate attracts a rotor unit toward the stator unit by a magnetic attracting force generated between itself and a rotor magnet fixed to the rotor unit. The conventional spindle motor provided with the magnetic attraction plate is disclosed in, e.g., Japanese Patent Laid-open Publication No. 2005-003115.
In the conventional spindle motor provided with the magnetic attraction plate, the planar portion of the magnetic attraction plate is bonded to the flat surface of a base frame. A strong magnetic attracting force acts between the magnetic attraction plate and the rotor magnet. This may possibly cause the magnetic attraction plate to be detached from the base frame. It is sometimes the case that the planar portion of the magnetic attraction plate and the flat surface of the base frame are bonded to each other with an insufficient bonding force. Thus, a need has existed to increase the bonding strength of the magnetic attraction plate.